Naturality of the disjoined triple #
The disjoined triple of a list (disjoinedTripleOf) is natural for the two operations the
independence of the shrinking open compares (functoriality for smooth morphisms [Kol07, 34.1] and
the empty blow-up convention [Kol07, 32]):
- pull-back along a local analytic isomorphism
h: the disjoined triple ofh^* Lfor the pulled-back triple is the pull-back of the disjoined triple ofLalong the last-stage lifth_r(the boundary families bytotalTransformSeqFrom_last_pullbackLiftLast, the original members byoriginalIdx_last_pullback_heq, the ideal sheaves bystageMap_last_pullbackLiftLast; [Kol07, 30.1] for the pull-back of a blow-up sequence); - padding by an empty blow-up: the disjoined triple of
cons h∅ (π^* L)(the disjoining list with one more, empty, first round;π : Bl_∅ M → Mthe blow-down) is an empty extension of the pull-back of the disjoined triple ofLalongπ_r— the extra exceptional divisor is empty (isEmptyExtension_totalTransform_of_eq_empty, propagated along the list byexists_isEmptyExtension_totalTransformSeqFrom_last).
Both are instances of disjoinedTripleOf_isEmptyExtensionOfPullback: a correspondence of the
boundary families at the last stages (PullbackCorr, Corr.lean) with matched original members,
plus the equation of the ideal sheaves, gives the relation IsEmptyExtensionOfPullback of the
disjoined triples (the same ideal sheaf, the boundary an empty extension of the pulled-back
boundary) — the hypothesis under which the input family's IndifferentToEmptyMembers and
CommutesWithLocalIsos identify its values. Used by Canonicity.lean (through ValueNatural.lean)
for the independence of the shrinking open.
Empty extensions of pull-backs of triples #
T' on N is an empty extension of the pull-back of T along g: the same ideal sheaf,
and the boundary of T' an empty extension of the pulled-back boundary (the same nonempty members
plus extra empty members).
Equations
- One or more equations did not get rendered due to their size.
Instances For
A correspondence of the boundary families at the last stages with matched original members, together with the equation of the ideal sheaves, makes the disjoined triple of the one list an empty extension of the pull-back of the disjoined triple of the other.
Propagation of an empty extension along a list #
An empty extension on the same space is a correspondence across the identity.
The stage map of cons at the last stage #
The composite blow-down of cons hY rest at the last stage is the blow-down of the first
round after the composite of rest (stageMapAux_cons_succ).
The blow-down of an empty centre is a local analytic isomorphism #
The blow-down of an empty centre is a local analytic isomorphism (it is the analytic
isomorphism emptyBlowUpDiffeomorph as a function).
Naturality of the disjoined triple #
Functoriality of the disjoined triple for local analytic isomorphisms ([Kol07, 34.1]): the
disjoined triple of h^* L for the pulled-back triple is (an empty extension of, with no extra
member) the pull-back of the disjoined triple of L along the last-stage lift h_r.
The empty blow-up convention [Kol07, 32] for the disjoined triple: the disjoined triple of the
list padded by an empty first round, cons h∅ (π^* L), is an empty extension of the pull-back of
the disjoined triple of L along the last-stage lift of the blow-down π — the extra exceptional
divisor is empty.